Am-pm indicator for 24 hour clock

ABSTRACT

An AM-PM indicator for a digital clock wherein the indicator is positioned to the left of an hours drum and a geneva driver is integrally formed with the hours drum for moving a shutter to indicate AM or PM. A geneva gear having a cam integrally formed therewith is positioned between the geneva driver and the shutter for moving the shutter to an AM or PM position.

United States Patent Boyles [54] AM-PM INDICATOR FOR 24 HOUR CLOCK {75]Inventor: Robert L. Boyles, Wayland. Mass.

[73] Assignee: General Electric Company,

Bridgeport, Conn.

[22] Filed: May 28. I974 {2 [1 App]. No.: 473,769

(52) U.S. Cl. 58/125 C; 58/127 R [5H Int. Cl G04b 19/02; G041) l9/O6[58] Field of Search 58/4 R. 6 R, I25 C, I26 E, 58/l27 R [56] ReferencesCited UNITED STATES PATENTS 2.459.107 1/1949 Johnson 58119 Apr. 8, 19751601073 9/l97l Terada 58/6 3.823.552 7/l974 Boyles Sit/I25 C PrimaryE.\'aml'nerEdith Simmons .lackmon Attorney, Agent, or Firm-Leonard J.Platt; George R. Powers; John F. Cullen [57] ABSTRACT An AM-PM indicatorfor a digital clock wherein the indicator is positioned to the left ofan hours drum and a gcneva driver is integrally formed with the hoursdrum for moving a shutter to indicate AM or PM. A geneva gear having acam integrally formed therewith is positioned between the geneva driverand the shutter for moving the shutter to an AM or PM position.

6 Claims, 5 Drawing Figures PATENTEBAPR ms 3,875,740

SHEEIEQEZ AM-PM INDICATOR FOR 24 HOUR CLOCK BACKGROUND OF THE INVENTIONThis invention relates to an AM-PM indicator for a digital clock, andmore particularly. to a unique shutter mechanism which is actuated by anhours drum for indicating AM or PM.

In my co-pending application (GD-4474) Ser. No. 339,213 which is nowU.S. Pat. No. 3,823,552, filed Mar. 8, 1973. and assigned to the sameassignee as the present invention, there is disclosed a digital clockwherein hours, tens of minutes, and minutes numerals are positioned ondrums or wheels which are rotated by an electric motor in order to bringsuccessive numerals into position behind a viewing window. The drums orwheels are positioned between two support plates which are arrangedgenerally parallel to each other, and a geneva mechanism is positionedat the left of the numerals for driving an hours drum. The presentinvention is concerned with such a digital clock, and more particularly,to an AM-PM indicator for such a clock.

Accordingly it is a primary object of my invention to provide animproved AM-PM indicator mechanism for a digital clock having relativelyfew parts which may be readily manufactured, and it is also an object ofmy invention to provide an AM-PM indicator mechanism which may bereadily and uniquely combined with a digital clock of the type disclosedin the above mentioned co-pending application without increasing theoverall size of the clock.

SUMMARY OF THE INVENTION In accordance with one of the aspects of thisinvention, a digital clock includes a support plate and a rotatablehours drum positioned adjacent to the support plate. The hours drum isrotated as a function of time and includes suitable indicia for visuallydisplaying numerals from one to twelve. My improved AM-PM indicator isuniquely constructed to be actuated by the hours drum and is positionedgenerally within the space between the hours drum and the support plate.In order to achieve this, a geneva driver lug is integrally formed onthe hours drum and extends outwardly from the drum for driving a genevagear. The geneva gear includes an integrally formed cam for moving ashutter to indicate AM or PM. The integrally formed geneva gear and camare rotatably mounted on the support plate between the support plate andthe hours drum, and the shutter is pivotally mounted on the supportplate adjacent to the cam for actuation by the cam. The cam is shaped sothat the position of the shutter is changed each time the numerals ofthe hours drum change from the l 1 o'clock to the l2 o'clock position.In this manner, at noon when the numerals change from the l 1 oclock tothe 12 oclock position. the cam moves the shutter to its PM position andthe cam holds the shutter in its PM position through all of theconsecutive number changes of the hours drum until midnight isapproached. At that time, when the numbers of the hours drum change fromthe 11 oclock to the 12 oclock position, the cam moves the shutter toindicate AM.

With this unique simplified construction, the shutter and the integrallyformed geneva gear and cam are readily located within existing spacebetween the hours drum and a support plate without increasing the spacerequirements of the clock.

It can also be appreciated that relatively few parts are required forachieving my unique AM-PM indicator. All that is required is theaddition of an integrally formed geneva gear and cam and an elongatedshutter member. The geneva driver lug may be integrally formed with thehours drum at the same time that the hours drum is being molded. Thus, avery compact, exceedingly simple, and readily manufactured AM-PMindicator for a digital clock has been achieved.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and attendant advantagesof the invention will be apparent from the following description takenin connection with the accompanying drawing in which:

FIG. 1 is a front perspective view of a digital clock which includes myimproved AM-PM indicator mechanism;

FIG. 2 is a cross-sectional view of the clock illustrated in FIG. 1;taken substantially on the plane of 2:2 of FIG. 1;

FIG. 3 is a fragmentary cross-sectional view of the clock of FIG. 1including my improved AM-PM indicator mechanism taken substantially onthe plane of 3:3 of FIG. 2',

FIG. 4 is an enlarged perspective view of the integrally formed genevagear and cam for actuating the shutter of my improved AM-PM indicatormechanism; and

FIG. 5 is a fragmentary exploded perspective view of the clockillustrated in FIG. I, showing the components of my improved AM-PMindicator mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing andfirst particularly to FIGS. 1 and 2, there is shown a digital clockwhich includes my improved AM-PM indicator mechanism. As shown, thedigital clock includes three sets of pages 2, 4, and 6, for minutes.tens of minutes, and hours. respectively.

The digital clock may be driven by a conventional self-startingsynchronous motor 8. and as shown more particularly in FIGS. 1 and 5,the minutes and hours numerals may be printed or otherwise formed onboth sides of pages so that the relatively large numerals may bepresented in a clock which is relatively small. With particular regardto the hours display indicator 6, l2 numerals are required for the hoursdisplay, and as shown in FIG. 5, this is accomplished by using sixpanels 8, 10, l2, l4, l6, and 18, which are pivotally mounted on flanges20 and 22 of an hours drum 24.

Two support plates 26 and 28 are arranged generally parallel to eachother for supporting the hours drum 24, a tens of minutes drum 30, and aminutes drum 32. A geneva gear mechanism 34 is located at the left ofthe numerals, as shown more particularly in FIG. 2, for driving the tensofminutes drum 30 and the hours drum 24. As shown, a geneva driver cam36 is arranged in engagement with a geneva gear 38 that is integrallyformed with the flange 20 of the hours drum for driving the hours drumone increment each hour. Since numerals are formed on both sides of thepages 8, l0, 12, 14, I6, and 18, it can be appreciated that the genevadriver mechanism for the hours drum rotates the hours drum at the rateof two complete revolutions every l2 hours. and naturally, fourrevolutions every 24 hours.

The mechanism for flipping the pages 8, 10, 12, 14, I6, and 18 todisplay numerals which are formed on both sides of the hours pages, isuniquely incorporated with support plate 26. As shown more particularlyin FIG. 5, a generally circular skirt member 40 is integrally formedwith the plate 26 and extends outwardly to the right in order to flipthe pages. As illustrated, the skirt 40 does not extend 360 but isformed with a gap or cut-out portion 42 of approximately 30 for tippingand flipping the display pages 8, 10, 12, 14, 16, and 18.

With this construction, as the drum 24 is rotated and one of the pagesreaches the cut-out portion 42 of the skirt, it is not confined by theskirt and the leading portion of the page moves outwardly beyond theskirt. Thus. as the page moves through the gap or cut-out portion of theskirt, it abuts a lower edge cam portion 44 of the skirt which flips thepage to display a new numeral. It can be appreciated that after the pagehas been flipped to display a numeral which had been posi tioned on theback side of the page, the skirt 40 will hold the page in its desiredposition until it again reaches the gap 42 in the skirt.

As shown more particularly in FIG. 1, a suitable plastic lens plate 46may be positioned in front of the numbers drums for providing a coverfor the drums, for suitably spacing the plates 26 and 28, and forholding a lamp 48 to illuminate the numerals.

The details of the mechanism for supporting and driving the hours drum24 do not form a part of this invention and are described andillustrated in greater detail in my co-pending application (6D-4474)Ser. No. 339,213, filed Mar. 8, I973, and assigned to the same assigneeas the present invention. However, in accordance with the instantinvention, the hours drum 24 is utilized for driving my improved AM-PMindicator and the support plate 26 is utilized for uniquely supportingand guiding my improved AM-PM indicator.

AM-PM IN DICATOR According to this invention, there is combined with theaforedescribed digital clock elements, an AM-PM indicator mechanismwhich is uniquely positioned within the space between the left side ofthe hours drum 24 and the support plate 26. As shown more particularlyin FIGS. 2, 3, and 5, the principal component of the AM-PM indicator isa shutter 60. As illustrated, the shutter 60 includes a lever 62 whichmay be formed of an elongated piece of sheet metal which is pivotallymounted on the inside ofthe support plate by means of a pivot 64. Theshutter lever 62 extends generally forwardly and upwardly above anenlarged central aperture 66 which is provided in the support plate, andas illustrated in FIGS. 3 and 5, the side and front wall portion of thesupport plate 26 is formed to include an aperture 66 for receiving aforward portion 68 of the shutter lever 62.

The shutter 60 also includes a flag-like element 70 which is located atits forward portion. In the preferred embodiment illustrated. the flag70 is constructed as a separate element so that it may be readilyconnected to the shutter lever 62 by means ofa pin and slot connection72, and 74. However, it can be appreciated that the shutter 60 includingits flag 70 could be formed as a single member.

As illustrated more particularly in FIG. 5 and FIG. 3, it can be seenthat the skirt portion 40 of the support plate which is utilized forflipping the pages of the hours drum 24, may be provided with agenerally flat, inclined front surface 78 for forming a suitable shelfguiding surface for the movable flag member 70.

With the construction thus far described, it can be appreciated that theshutter 60, 62, 70, should be retained in one position during the AMhours and in another position during the PM hours in order toappropriately display AM and PM. In order to achieve this, a uniquegeneva gear and cam mechanism 80 is provided for holding the shutter 60in an upper position during the PM hours and for holding the shutter 60in a lower position during the AM hours. A geneva driver lug 82 isintegrally formed with the flange 20 of the hours drum 24 for driving ageneva gear 81 one increment during each complete rotation of the hoursdrum or one increment every 6 hours. Thus, as shown more particularly inFIG. 4, geneva gear 81 is shaped to include four lobes 84, 86, 88, and90, so that it may be rotated four increments during a 24 hour period.Since it is only necessary to move the shutter to two differentpositions during a 24 hour period, a cam 94 which is integrally formedwith the geneva gear 80, is provided with an appropriate cam surface 104for holding the shutter in only two positions. As illustrated in FIG. 3,the integrally formed cam and geneva gear 81-94 is rotatably mounted onthe inside of the support plate 26 by means ofa bearing 100, and therelatively thin shutter lever 62 is sandwiched between the support plate26 and the lobes of the geneva gear so that a cam surface 102 of theshutter may readily ride on the surface 104 of cam 94.

In operation, as the hours drum 24 is moved from an 11 AM position to a12 noon position, the geneva driver lug 82 of the hours drum rotates thefour lobe geneva gear 81 one increment. During this incremental movementof the geneva gear 81, the cam 94 which is integrally formed with thegear will move one increment to lift the shutter 60 and its flag toindicate PM. The next movement of the geneva gear 81 will occur when thehours drum is moved from 5 to a 6 oclock position, however, during thismovement the cam surface 104 will continue to hold the shutter 60 in itsraised position. When the numerals of the hours drum are next moved froman 11 position to a 12 midnight position, the geneva gear 81 will berotated its next increment and the cam 94 which is integrally formedwith the geneva gear will lower the shutter 60 to indicate AM. The nextmovement of the geneva gear will occur when the hours drum is moved toits next 6 position, and naturally during this movement, the shutterwill be retained in the lower AM position.

In accordance with a further aspect of my invention, the shutter 60 isuniquely incorporated with AM-PM indicia so that a relatively smallshutter may be utilized for providing a relatively large AM-PM display.In order to achieve this, the left portion of the lens 46 is made opaqueor is provided with a black background member in the vicinity of theshutter 70 and the letters PM are printed in white on the blackbackground. The letter P includes a generally vertical elongated bar 101at its left, two generally horizontal bars 103 and 105 extending to theright from the vertical bar 101 and a relatively short vertical bar 107connecting the right end portions of the horizontal bars 103 and 105. Inorder to form the letter A, a generally vertical transparent bar 106 ispositioned below and in line with the generally vertical short bar 107which is utilized for forming the letter P and extends downwardly fromthe short bar. The flag 70 of the shutter is positioned behind the bar106, and as shown more particularly in FIG. 5, it includes a coloredportion 108 which is the same color as the background of the lens andanother colored portion 110 which is the same color as the bars of theletters to be displayed. With this arrangement, it can be appreciatedthat when the darkened portion 108 of the shutter is positioned in frontof the bar 106, the letter P will be displayed and when the shutter islowered to position the lighter colored portion 110 in front of the bar,the letter A will be displayed.

In the embodiment illustrated. the shutter lever 62 is positioned abovethe cam surface 104 and the force of gravity may be utilized for holdingthe shutter lever on the cam 94 for allowing the shutter lever to movedownwardly under the force of gravity when the hours drum is moved fromthe 11 oclock position to the 12 oclock position at midnight to displaythe letters AM. In order to insure more positive movement of the lever60 when it is moved toward the axis of the hours drum, a spring may beprovided for urging the lever toward the cam 94. As shown moreparticularly in FIGS. 3 and 5, this may be achieved with the use of arelatively thin wire spring member 112 which may be shaped asillustrated. In order to suitably hold the ends of the spring, anaperture 120 may be formed in an end portion of the shutter lever 62 anda lug 122 may be integrally formed with the support plate 26 forsuitably holding the upper end of the spring. With this arrangement, thelever 60 is resiliently urged in a counterclockwise direction aboutpivot 64, as shown in FIG. 3.

In view of the foregoing, it can be appreciated that my improved AM-PMindicator mechanism may be formed of relatively few parts which may bereadily connected to each other and incorporated in a digital clock ofthe type disclosed in my above mentioned copending application withoutincreasing the overall space requirements of the clock. Many of thecomponents may be simply integrally formed with other parts ofthedigital clock while the overall clock is being manufactured. Forexample. the geneva driver lug 82 may be integrally formed on the hoursdrum 24 at the same time that the flange and the geneva gear 38 of thehours drum are being formed. In regard to the support plate 26, the lug122 for holding the spring 112, apertures 130 and 132 for receiving thegeneva gear and shutter bearings. aperture 66 for receiving the forwardend of the shutter lever 62, and the inclined shelf 78, may all beformed at the same time that the support plate 26 is being molded. Thus.an exceedingly simple and reliable AM-PM indicator mechanism is achievedwith the use of relatively few parts which may be readily connected toeach other.

What I claim is;

I. An AM-PM indicator mechanism for a 24 hour digital clock comprising:

a. a support plate:

b. a rotatable hours drum positioned adjacent to said support plate.said hours drum having hours indicia 6 for visually displaying numeralsfrom one to twelve; c. a geneva driver means integrally formed on saidhours drum extending outwardly from said hours drum and rotatable withsaid hours drum as a function of time;

d. a geneva gear mounted for rotation on said support plate adjacent tosaid hours drum. said geneva gear being positioned for cooperation withthe driver means so that the geneva gear is rotated each time the hoursdrum and the geneva driver means on the hours drum advances from an lloclock position to a l2 oclock position;

e. a cam integrally formed with said geneva gear;

f. an AM-PM indicator shutter positioned for actuation by the cam thatis integrally formed with the geneva gear, said cam being shaped so thatthe position of the shutter is changed each time the numerals of thehours drum change from 11 to 12.

2. An AM-PM indicator mechanism as defined in claim 1 wherein the AM-PMindicator shutter is sandwiched between the geneva gear and the supportplate in order to suitably confine the shutter for movement on the camwhich is integrally formed with the geneva gear.

3. An AM-PM indicator mechanism as defined in claim 1 wherein a springis positioned between the support plate and the shutter for urging theshutter downwardly toward the cam which is integrally formed with thegeneva gear.

4. An AM-PM indicator mechanism as defined in claim 1 wherein saidshutter comprises:

a. an elongated shutter lever formed of a relatively thin piece of sheetmetal, said shutter lever extending forwardly above the cam which isformed with the geneva gear and through a slot which is formed in thesupport plate and being pivotally mounted to a rear portion of saidsupport plate; and,

b. a generally flat indicator member connected to said lever formovement therewith, said indicator member being arranged generallyperpendicular to the lever so that it may be viewed at the front of theclock.

5. An AM-PM indicator mechanism as defined in claim 4 wherein a skirt isformed on said support plate for partially surrounding the hours drum,and the skirt includes an inclined, generally flat surface for suitablyguiding and holding the generally flat indicator member.

6. An AM-PM indicator mechanism for a 24 hour digital clock comprising:

a. a support plate;

b. a rotatable hours drum positioned adjacent to said support plate.said hours drum having hours indicia for visually displaying numeralsfrom one to twelve;

c. a geneva driver lug integrally formed on said hours drum extendingoutwardly from said hours drum and rotatable with said hours drum at tworevolutions every 12 hours;

d. a four lobe geneva gear mounted for rotation on said support plateadjacent to said hours drum, said geneva gear being positioned generallyabove the geneva driver lug for cooperation with the driver lug so thatthe geneva gear is rotated each time the hours drum and the genevadriver lug on the hours drum advances from an 1 1 oclock position to a12 o'clock position and from a 5 oclock position to a 6 o'clockposition;

e. a cam integrally formed with said geneva gear and positioned betweenthe geneva gear and the support plate;

earn from a 5 to a 6 oclock position, is lowered during the nextmovement of the cam to a l2 midnight position, and is retained in thelowered AM position during the next cam movement from a 5 to a 6position.

1. An AM-PM indicator mechanism for a 24 hour digital clock comprising:a. a support plate; b. a rotatable hours drum positioned adjacent tosaid support plate, said hours drum having hours indicia for visuallydisplaying numerals from one to twelve; c. a geneva driver meansintegrally formed on said hours drum extending outwardly from said hoursdrum and rotatable with said hours drum as a function of time; d. ageneva gear mounted for rotation on said support plate adjacent to saidhours drum, said geneva gear being positioned for cooperation with thedriver means so that the geneva gear is rotated each time the hours drumand the geneva driver means on the hours drum advances from an 11o''clock position to a 12 o''clock position; e. a cam integrally formedwith said geneva gear; f. an AM-PM indicator shutter positioned foractuation by the cam that is integrally formed with the geneva gear,said cam being shaped so that the position of the shutter is changedeach time the numerals of the hours drum change from 11 to
 12. 2. AnAM-PM indicator mechanism as defined in claim 1 wherein the AM-PMindicator shutter is sandwiched between the geneva gear and the supportplate in order to suitably confine the shutter for movement on the camwhich is integrally formed with the geneva gear.
 3. An AM-PM indicatormechanism as defined in claim 1 wherein a spring is positioned betweenthe support plate and the shutter for urging the shutter downwardlytoward the cam which is integrally formed with the geneva gear.
 4. AnAM-PM indicator mechanism as defined in claim 1 wherein said shuttercomprises: a. an elongated shutter lever formed of a relatively thinpiece of sheet metal, said shutter lever extending forwardly above thecam which is formed with the geneva gear and through a slot which isformed in the support plate and being pivotally mounted to a rearportion of said support plate; and, b. a generally flat indicator memberconnected to said lever for movement therewith, said indicator memberbeing arranged generally perpendicular to the lever so that it may beviewed at the front of the clock.
 5. An AM-PM indicator mechanism asdefined in claim 4 wherein a skirt is formed on said support plate forpartially surrounding the hours drum, and the skirt includes aninclined, generally flat surface for suitably guiding and holding thegenerally flat indicator member.
 6. An AM-PM indicator mechanism for a24 hour digital clock comprising: a. a support plate; b. a rotatablehours drum positioned adjacent to said support plate, said hours drumhaving hours indicia for visually displaying numerals from one totwelve; c. a geneva driver lug integrally formed on said hours drumextending outwardly from said hours drum and rotatable with said hoursdrum at two revolutions every 12 hours; d. a four lobe geneva gearmounted for rotation on said support plate adjacent to said hours drum,said geneva gear being positioned generally above the geneva driver lugfor cooperation with the driver lug so that the geneva gear is rotated90.degree. each time the hours drum and the geneva driver lug on thehours drum advances from an 11 o''clock position to a 12 o''clockposition and from a 5 o''clock position to a 6 o''clock position; e. acam integrally formed with said geneva gear and positioned between thegeneva gear and the support plate; f. an AM-PM indicator shutterpositioned between said geneva gear and said support plate for actuationby the cam that is integrally formed with the geneva gear, said cambeing shaped so that the shutter is raised each time the hours drummoves from an 11 to a 12 noon position, is retained in its raisedposition during the next movement of the cam from a 5 to a 6 o''clockposition, is lowered during the next movement of the cam to a 12midnight position, and is retained in the lowered AM position during thenext cam movement from a 5 to a 6 position.